Fast rendering techniques for rasterised graphic object based images

Abstract

Disclosed are methods, apparatus ( ) and computer readable media for rendering at least one graphic object ( ) described by at least one edge ( ) into a raster pixel image ( ) having a plurality of scan lines and a plurality of pixel locations on each scan line. For each scan line, coordinates of intersection of those edges of the objects that intersect the scan line are determined in a predetermined order. This is preferably achieved by processing edge records ( ) using a number of buffers ( ) thereby enabling efficient sorting of edge intersections into order. For each adjacent pair of edge intersections, information ( ) associated with the corresponding object is examined to determining a set of active objects ( ) for a span of pixel locations between the corresponding pair of edge intersections. For each span of pixel locations, the corresponding set of active objects is used to determine ( ) a value for each of the locations within the span. The information may include one or more of a fill count, a clip count and other factors. A compositing model accommodating opacity is also disclosed, as are stack operations used to facilitate rendering and other features which contribute to fast processing of image components.